And let’s not forget that this August will mark 20 years since the release of “Smells Like Teen Spirit,” the song that signaled a seismic shift in modern music—and made megastars of Grohl’s previous band, Nirvana.

All of which seems to have left Grohl, 42, feeling a tad, well, old. “It’s weird when there’s a kid on the bill who comes up and says, ‘Your band was my first concert,'” he muses. “You just think, ‘Oh no. I’m that guy, now? What am I, f—ing Gandalf?’”

In truth, few people would confuse the Foos overlord for the Lord of the Rings wizard. Apart from anything else, Gandalf doesn’t drop the F-bomb nearly as much as Grohl who, after the jump, foul-mouthedly talks about Wasting Light, Back and Forth, and what it was like to play “Smells Like Teen Spirit” for the first time in 18 years.

Entertainment Weekly: You recorded Wasting Light in your garage. Where did you put your dartboard, garden furniture, and Swedish porn collection?

Dave Grohl: It’s funny, whenever I say a made a record in the garage, people just assume that I have like a f—-ing Lear jet parked in there, or something. That it’s this cavernous f—ing hangar space. But really there’s old luggage, a couple of bikes. It’s big enough to put one minivan in. That’s it. No dartboard. I’m so not macho. It’s crazy. My man cave is so not a man cave.

On the song “Arlandia” you sing “Fame, fame go away/Come again some other day.” Did no one have the cojones to tell you it’s actually supposed to be “rain”?

All the years playing live have f—ed with my hearing. So I just thought it was “fame.” [Laughs] No, there’s something about the sing-song cadence of children’s music that has its place in rock. Kurt [Cobain] used to talk about that. He used to try to simplify songs so that they sounded like nursery rhymes. He put so much importance on melody. He really downplayed his lyrical skills. He always said, “Melody first and lyrics second.” In his case, I thought they were both equal, you know. But there’s something about nursery rhyme patterns that are just undeniable.

You recruited your Nirvana band mate Krist Novoselic to play bass on the track “I Should Have Known.” And you also got Nevermind producer Butch Vig to oversee the CD. You must have known people would get pretty excited when they heard the three of you were working together again.

Deciding to work with Butch on this record was a big step for me, personally. Because I’ve had to walk this really fine line between the Foo Fighters and Nirvana for 17 years. I owe everything to Nirvana. But I can’t let that overshadow the future. For the first few years, I didn’t even want to talk about Nirvana. Partly because it was just painful to talk about losing Kurt but also because I wanted the Foo Fighters to mean something.

After a while it became easier to talk about. But there were certain things that were off limits. Like I couldn’t have made the first Foo Fighters album with Butch. And I don’t think I could have made the second one with him. It got to the point where I felt like, maybe it’s finally time. But I was caught in this uncomfortable place: “We’re coming up on the 20th anniversary of Nevermind, so do I have to wait another ten f—ing years?”

Then I started thinking, “This is my f—ing band. Why would I let anyone else influence what I want to do musically? F— that, let’s work with Butch.” And then you start to free yourself from all of those restrictions that have been placed upon you. Krist is really no stranger to the Foo Fighters. He’s recorded with us in the studio before, he’s played with us live. But you put Krist and Butch and me in the studio for the first time in 20 f—ing years it becomes more than just a guest appearance and a day in the studio. There’s a lot more weight to it. Which I totally understand. But to me, having Krist come down and play on the record was more of a personal opportunity. I just thought, “What a trip, to sit with Krist and Butch and Pat [Smear, Nirvana and Foo Fighters guitarist] in the studio together.” Because that was never supposed to happen again. It was pretty huge.

The day we finished the record, we had this club gig to do. It was in this little bar down the street, a surprise show. I invited Krist to come down and play a song. We wanted to play “Marigold,” which was the b-side of the “Heart-Shaped Box” single, and it was the only Nirvana song I sang. I said, “Krist, for the encore, I’ll play drums, you play bass, Pat plays guitar, we’ll do that song. And that’ll be the first time we’ve been together onstage since Nirvana ended.”

So we go to the studio that day to practice. We run though the song once and then Krist says, “Hey you guys want to do some moldy oldies?” Me and Pat look at each other and go, “Okay, what do you want to do?” He says, “Let’s do ‘Smells Like Teen Spirit.'” “Okay.” I hadn’t played that song in 18 years. I haven’t even played the drum beat to that song in 18 years. And we played it. And there’s only one person in the studio, who was Scott, the studio manager. Halfway through the song he opens up the door and he looks in, and watches for a minute and closes the door again. We ended the song and look at each other like, “That was strange.” We walked out and Scott looked at us and said, “Yeah, it sounded pretty good. You guys should keep that.”

Watching Back and Forth I was surprised by how many ups and downs the Foos have been through.

We’ve been pretty quiet about the personal, private side of the band. We always believed a little mystery is important to rock’n’roll. But we had gotten to the point where… Did you see the Tom Petty documentary?

Yes. I’m a huge Tom Petty fan.

Me too. It’s four hours long! So I thought, you know, maybe it’s time that we tell people the story. If we wait any longer, we’re going to wind up with a four-hour-long documentary.

Speaking of Tom Petty, you mention in the documentary that you almost became his drummer after the end of Nirvana.

It was interesting. 1994 was a really weird year. The beginning of that year was the first time I’d ever been in a band that I really didn’t want to be in anymore. The last Nirvana tour was kind of difficult. The mood was off and it was kind of depressing. I don’t know if anybody wanted to be there. And then Kurt died and there was a long period of feeling lost and confused and not knowing what else to do.

Then I got a call from somebody at Tom Petty’s management that he wanted me to do SNL. My first reaction was, “What the f—? He couldn’t find a real drummer?” Of course, I jumped at the opportunity. Because I’ve always loved Tom Petty. Even when I was a stubborn, cynical, punk-rock asshole, I still lived Tom Petty. Because I felt like he was a stubborn, cynical, punk-rock asshole too. So, it was interesting. I easily could have become someone’s drummer. But I didn’t want to be anyone’s drummer.

The first half of the documentary largely consists of people either leaving the Foo Fighters or threatening to leave the Foo Fighters. How bad is your body odor problem?

Actually, I didn’t start sweating until I had children. That was one of the first things I realized when my daughter Violet was born—I started getting wicked BO. You know there’s a difference between basketball BO and stress BO? This was definitely stress BO. Like, new dad BO.

Seriously, how would you rate your man management skills given the swift turnover of personnel in the early years of the Foo Fighters?

I had never been in charge of anything. I’d always worked for someone. I worked for a furniture warehouse. I did masonry. I always had a boss yelling at me. So I’d never been in charge of an organization. And, f—, I was young. I was 25 or 26 years old. It’s different now. The way I deal with things in the Foo Fighters now is a lot different than it was 16 years ago.

When you put together a band, there’s always this “all for one and one for all” ethic. You get together like a gang of school hoodlums, you know. And that works for a while, until it becomes something more than just a gang of kids. And that’s when it gets tricky. Most of the growing pains that we went through, every f—ing band in the world’s gone through. We just had to go through ours in public.

Had I not been in Nirvana, nobody would have cared about our first drummer. Nobody would have cared about Pat quitting and coming back. But because there was so much attention on this band when it first started, all of that was done in public and it was uncomfortable. But I wouldn’t change a thing. Everyone that happened in the first three or four years is totally justified and I have a good conscience about all of it. But it was tough, man.

You’ve said the documentary was hard to watch. Is that because of the footage in which you have dyed blond hair?

That’s probably the one thing I do regret. One of my favorite punk rock drummers, his name was Chuck Biscuits. He played for Black Flag and the Circle Jerks. I remember seeing a picture of him where he had dyed his hair white, and it was growing out. So half of it was dark and half of it was white. I thought it was coolest f—ing thing I’d ever seen in my life. So I dyed my hair. F—ing idiot. I looked like a total messy drag queen. It was horrible.

You’re in the new Muppets movie. What do you do in that?

I don’t think I’m allowed to talk about it.

Okay then, who’s the hottest Muppet?

I think everybody had Miss Piggy fantasies. She seemed sassy. I always had a thing for Grover, to be honest. Grover and his alter ego, Super Grover.

This a threesome fantasy?

No, I actually prefer Super Grover. I had a Super Grover doll growing up. Super Grover was very clumsy, he wasn’t very good-looking. But in his own way he’d always save the day. I’ve never wanted to f— a Muppet, if that’s what you’re asking. [Laughs]

You’ve kind of been feuding with Ryan Murphy recently [earlier this month, Grohl told an interviewer “It’s every band’s right, you shouldn’t have to do f—ing Glee]. If you were trapped in an elevator with him, what would the conversation be like?

The point I was so eloquently trying to make is that bands have to understand it’s okay to exist in their own world, outside of the conventional system. You shouldn’t feel pressured to do anything. I don’t think any band should be told what to do, or made to feel guilty for not doing something. You know, I could sit down and have a beer with anybody. I can hang out with the f—ing Jonas Brothers and then turn around and do shots of whiskey with Pantera. To me, at the end of the day, people are just people and I’m never one to hold a grudge. There’s so few people that I’ve ever been upset with for longer than a little while.

When you go for your tour insurance medical, is it the full rubber gloves workup?

I’ve never had tour insurance, I don’t think. Who am I, Britney Spears? I got my ears checked once. Once. I’ll never do that again. F— that. They were like, “You’re deaf.”

Going back to your single days, what’s the difference between drummer groupies and lead singer groupies?

I think lead singer groupies just want to be famous, whereas drummer groupies just want to get laid.

Foos drummer Taylor Hawkins has said that if John Bonham and Paul McCartney had a love child, it would be you. Does he have any idea at all about how babies are actually made?

[Laughs] He is a drummer, after all.

You once got Bobcat Goldthwait to do an interview pretending to be you. Do you now wish you’d done that for this interview?

I haven’t seen Bob in so long. Bob’s a good interview, I have to say. I think in that one he convinced the journalist that I was totally into, like, jazzercize and deer hunting. Yeah, That really kicked off my career in the press. That’s when people wanted to start talking to me. “Oh, he’s funny? Yeah, I’ll do an interview with that guy!”